I don't want to be That Person, but it seems to me that my book The Fire Mages ticks almost all your boxes. It follows a girl from age fourteen to early twenties, who becomes very powerful, and there's even a time in a sort of magical academy. Here's the link on Amazon.
ETA link.
Hi folks! I have a new book out this Friday (9th Jan). The Fire Mages is an epic fantasy adventure. Kyra is a girl with a determination to make something of her life, whose ambitions are derailed by her unusual magical abilities. Featuring a cranky mage, a fire-raising heir and a mysterious city with magic so powerful even mages are afraid to go there.
You can pre-order now for $0.99; it will stay at that price for a couple of weeks. Or you can buy the paperback right away, and get the ebook free later. Or you can borrow it for free after release through Kindle Unlimited or your Prime subscription.